USS Monitor: How was it modified during its brief service? How did it sink? Remarkable 3D images, animation will add to our appreciation of ironclad, crew

View of the bow and forward section, with armor belt section nearby; 3D model of USS Monitor as it appeared in July 1862; another view of the inverted hull, captured last fall. (Northrop Grumman)

New breathtaking, high-resolution images of the USS Monitor wreck are available on a government website that includes animation of the famous ironclad’s sinking and 3D models of how it appeared at various times during its brief life.

NOAA’s Monitor National Marine Sanctuary rolled out the page – which includes a four-part timeline about the vessel – on Saturday after a presentation on the results of a September 2025 mapping of the wreck site off Cape Hatteras, N.C.

Sanctuary research coordinator Tane Casserley told an audience at Mariners’ Museum and Park in Newport News, Va., that the ironclad, despite damage from its March 1862 fight with CSS Virginia, its sinking ninth months later and artifact recovery projects 25 years ago, looks great.

“It is in fantastic shape, so the same armor belt that was built to repel cannonballs in the Civil War is now holding that cultural heritage together today,” he said. “I was surprised by just how intact things were.”

NOAA and its partners Northrop Grumman and Stantec showed off some of the sonar-produced images of USS Monitor, which was discovered in 1973. A Northrop Grumman unmanned underwater vehicle was equipped with a micro synthetic aperture sonar (µSAS) system during the expedition. The system is a big upgrade over old side-scan sonar.

The system penetrated low-visibility conditions to generate extraordinary imagery of the wreck and its surrounding debris field, including detailed views of hull remains and internal structure, according the museum.

The website features a 41-second animation of the Monitor’s sinking during a storm on Dec. 31, 1862. The clip shows the doomed ironclad bobbing in heavy seas and the “glub glub” of water as it dips beneath the surface and turns before slamming into the sea floor 240 feet down. The turret tumbles away upon collision.

John Broadwater (photo below), a maritime archaeologist who has been on numerous Monitor expeditions and is a former superintendent of Monitor Marine National Sanctuary, was among those attending Saturday’s program and his name was mentioned when the unveiling turned to the animation.

“Two of the developers of that animation came up to me and enthusiastically said they were glad to meet me," Broadwater told the Picket. "One said that when she was working on the sinking sequence, she had my Monitor book ('USS Monitor: A Historic Ship Completes Its Final Voyage'] in her lap, trying to follow my description of the sinking, which was based on archaeological evidence and long discussions with naval engineers, salvage experts and my colleagues at the Marine Forensics Committee of the Society of Naval Architects and Marine Engineers. From my perspective, Northrop Grumman and NOAA got it right."

Sixteen men, including four officers, perished when the Monitor went down. The remains of two sailors were found in the turret when it was recovered in 2002. The turret and hundreds of other Monitor artifacts have been or are being conserved at Mariners’ Museum and Park.

The vessel’s stern and part of the starboard side struck the sand as it landed upside down. The bow and forward section are still intact.

The new images shows the stern is gone, with some of that displaced by the recovery of the turret, anchor and other components from 1998-2002. (Image at left, Northrop Grumman)

The Picket asked Casserley for his thoughts on how the animation was done.

 “When the wreck was discovered in 1973, we observed damage at the stern and starboard side, as well as rudder missing from the site. From these observations and damage found to some of the aft bulkheads we recovered, we can theorize how the vessel sank -- which is reflected in the animation.”

Images on the website show a detached part of the ironclad’s armor belt and some wire rigging used during salvage operations. Navy divers had to remove a section of the belt and some hull plating during the recovery of the turret, which rested beneath the vessel.

The sonar imagery is so precise you can see an automobile tire or two that somehow came to be in the area.

Mariners’ Museum and Park -- which houses thousands of Monitor artifacts -- said the aim is to improve interpretation and perhaps protection of the wreck, which is slow deteriorating.

Those interested in 3D modeling can turn to the NOAA website and Sketchfab to see three reconstructions of USS Monitor produced by Northrop Grumman, a defense contractor. Viewers can use their mouse to see the vessel from different perspectives.

Built as a prototype for a brand new type of warship, Monitor was continually improved during its brief life afloat in 1862. These improvements included different deck layouts.

3D deck view of the Monitor as it appeared during the Battle of Hampton Roads (Northrop Grumman)

The first image shows the ironclad as it appeared for the March 8-9, 1862, Battle of Hampton Roads against the CSS Virginia (Merrimack). In July 1862, the Monitor got a modified pilot house at the bow and extended air intake vents and smoke boxes toward the stern.

The third model is an artist’s interpretation of work in November 1862 at the Washington Navy Yard. Repairs and further improvements were undertaken. A telescoping smokestack and taller air ventilation boxes were fitted, which improved efficiency, according to NOAA.

Saturday morning’s presentation also heralded the Monitor’s role as an artificial reef and thriving ecosystem. A Northrop Grumman “Wreck to Reef” visualization shows how the wreck hosts fish, invertebrates and plant life.

Kelly Swindle, a senior marine biologist with Stantec, said the team took environmental DNA sampling from the water around the wreck and identified several fish, including the lancer dragonet, largehead hairtail, pearly razorfish and the twospot flounder.

Cannon damage on USS Monitor after clash with CSS Virginia (Library of Congress)

Casserley told the audience people can learn so much new about the ironclad from the comfort of their armchair. “We can now bring Monitor to you virtually.”

“It's one thing to read a historical account and it's a whole other experience seeing it come to life before your eyes,” he told the Picket in the email.

The sonar images help the agency track changes over time “by showing the hull and armor belt integrity with hyper-accuracy. It will provide the sanctuary with a valuable baseline for future monitoring and inspire the next generation of marine scientists and archaeologists alike,” Casserley wrote in the email.

Broadwater said he was impressed by Northrop Grumman’s technology and the educational products developed in cooperation with the museum.

 “I only wish we'd had that technology back before we recovered the engine and turret. I tried hard to get an accurate 3D image of the Monitor before we disturbed the hull.”

Wow factor: Hi-res views of USS Monitor will be unveiled March 7 at Battle of Hampton Roads event. The aim is to promote education, protection in a new way

Monitor has been on the sea floor163 years (NOAA/GFOE); sonar vehicle used in 2025 (Tane Casserley/NOAA)

The public will have its first opportunity March 7 to see new “groundbreaking” sonar-produced images of the USS Monitor wreck and a 3D reconstruction of what the famous Union ironclad looked like before it sank during a storm off Cape Hatteras, N.C.

Monitor National Marine Sanctuary and Northrop Grumman officials will make the 10 a.m. presentation during the annual Battle of Hampton Roads event at the Mariners’ Museum and Park in Newport News, Va.

About 60 people will be able to attend the program at the museum’s Explorers Theater. Those unable to attend can register here to watch the presentation online.

A Northrop Grumman unmanned underwater vehicle created scans of the December 1862 wreck site during high-resolution mapping in September 2025. The vehicle is equipped with a micro synthetic aperture sonar (µSAS) system.

A Northrop Grumman vessel deployed the technology last September (Tane Casserley/NOAA)

The system penetrated low-visibility conditions to generate extraordinary imagery of the wreck and its surrounding debris field, including detailed views of hull remains and internal structure, according the museum.

Discovered in 1973 and designated as the nation's first national marine sanctuary in 1975, USS Monitor rests nearly 240 feet below the ocean's surface.

“Along with these scans, Northrop Grumman created several new visualizations of Monitor for us to help interpret its historic legacy and its role now as a thriving reef,” sanctuary research coordinator Tane Casserley told the Picket.

The museum is hosting the daylong event remembering the March 8-9, 1862, clash between the innovative Monitor and the Confederacy’s Virginia.

Cannon damage on USS Monitor after clash with Virginia (Library of Congress)

The venue -- which houses thousands of Monitor artifacts -- said the aim is to improve interpretation and perhaps protection of the wreck, which is slow deteriorating.

Officials have been finalizing speakers for the program and have declined to release any of the sonar images ahead of the unveiling. Among those joining in the presentation are NOAA, museum and Northrop Grumman officials and technical experts.

The day’s activities (see details here) are aimed at inspiring young visitors to explore engineering, science and cutting-edge technology.

"By unveiling this new technology alongside hands-on STEM activities, we’re showing the community that history and innovation go hand-in-hand,” said Will Hoffman, director of conservation and chief conservator at the Mariners’ Museum. “These experiences provide visitors a new window into the past, enabling people to engage with USS Monitor through a different lens, and potentially, drawing in new audiences of all ages to learn about the little ship that saved the nation.”

According to a sanctuary article, all data products from the project -- including 3D models, visualizations, and animations -- will be transferred to NOAA and made available for public use, “supporting transparency, education and long-term stewardship of the site.”

Casserley said images and more details on the project will be released March 7 at the sanctuary website.

Brace yourself as we update you on U.S.S. Monitor mystery maker's mark and explain how two rods stabilized ironclad's remarkable revolving turret

Braces under, near guns in recovered turret (top); rendering of them with crew (MMP, Andy Hall)

The 600-page “Drawings of the U.S.S. Monitor, published in 1985, depicts the venerable Civil War ironclad from practically every angle. Scores of sketches demonstrate the exacting work of the draftsmen – with some components drawn to the inch.

“To the men who had the imagination, knowledge and skill to produce these drawings and the Monitor,” reads the dedication in the volume, written by Ernest W. Peterkin for the North Carolina and federal governments.

I continue to marvel at the design and engineering skills of those who made the vessel that changed naval warfare in a single battle with the CSS Virginia in March 1862. My recent foray into learning a bit more about the vessel’s circular, ingenious turret – and its supporting braces -- put me back in touch with experts on Monitor.

As I further studied the turret after communicating with them – I had an amusing observation.

A drawing (below) at the top of the publication – “transverse section through turret” -- features a cross-section of Monitor, with the turret resting on top of a spindle.

Oh my, I thought. The turret and rod combined look like a child’s spinning top!

Transverse section through turret shows spindle beneath (Drawings of the Monitor)

The revolving turret was no toy, however. It housed two XI-inch Dahlgren guns that could smash both ship and man. But to make the setup work, designer John Ericsson had to overcome challenges with the turret, dubbed a “cheesebox on a raft.”

“It was enormously heavy … (and) was designed to be turned by machinery rather than by hand,” Civil War naval expert Andy Hall told me in a recent email.

“To improve this efficiency, Ericsson recognized that it was necessary to relieve part of the weight of the turret on the rollers around its perimeter by ‘jacking up’ the turret a bit, temporarily placing much of its weight on its central vertical spindle. To prevent the turret structure from sagging, Ericsson included diagonal braces from the central roof beam to the base forward, aft and on either side of the turret that could be adjusted using enormous turnbuckles.”

Aft diagonal brace with ULSTER, highlighted at right, click to enlarge (Courtesy Mariners' Museum and Park)

Maker's mark 'Ulster' leaves questions

The two diagonal support braces (forward and aft) inside the turret have been of interest to me following the 2017 announcement by The Mariners’ Museum and Park in Newport News, Va., that Monitor conservators removing corrosion from the aft brace uncovered the word “ULSTER.” It’s the first time a maker’s mark was found in the turret.

Officials theorized the two wrought-iron braces – which have undergone conservation since 2016 -- were produced by Ulster Iron Works in Saugerties and added to the turret interior. The scenic city along the Hudson River is about 100 miles north of New York City, where Monitor was assembled in late 1861 and early 1862.

The company, which operated from 1827 to 1888 and took advantage of iron deposits in the area, was a Navy contractor.

Cannon damage on USS Monitor after clash with Virginia (Library of Congress)

“While this firm was never mentioned as a supplier during the Monitor’s construction at Continental Iron Works, it is now believed that Ulster provided materials for modifications to the ship while it was undergoing sea trials at the Brooklyn Navy Yard,” says the museum, which houses the USS Monitor Center, home to artifacts and items still being conserved after they were recovered off Cape Hatteras, N.C., more than two decades ago.

I have been mesmerized since the announcement by the mystery of the Ulster mark.

I reached out last month to Will Hoffman, Monitor project manager, to see whether conservators have since confirmed any link between the vessel and Ulster Iron Works.

The short answer: No.

Hoffman has cited papers from Ulster Iron Works in the collection of William L. Clements Library at the University of Michigan in Ann Arbor.

A summary of the collection includes this line: “Among the factors that contributed to the success of the Ulster Iron Works was the ability of the owners of the corporation to arrange for government contracts, especially contracts with the Navy, for providing iron products for use in rockets, ships, and other materials.” (At left, the forward and aft braces, courtesy of Mariners' Museum and Park.)

I reached out to the library to ask whether Ulster Iron Works records make specific mention of Monitor.

Terese Murphy, head of reader services, says a bound volume has entries through 1863 – a year after Monitor was lost in a storm.

Murphy wasn’t able to find mention of Monitor, but kindly sent me photos of the pages that would have mentioned the ironclad. I wasn’t able to make all the writing, but I, too, didn’t see the Monitor in the notes – many descriptions of technology and project summaries. It is possible that the names of the vessels for projects were not inscribed. The descriptions are very technical.

The manufacturer, which drew workers from as far away as England and Wales, was known for using European technology. A process called “double puddling” could produce appreciable amounts of high-grade bar iron.

1862 page from volume on Ulster Iron Works (Courtesy Clements Library, U. of Michigan)

Hoffman says, despite some research by his staff, he has not learned much more.

“It kind of went dead after that,” he says of the search for the Ulster connection. “We know these braces are additions.” They are not shown in original blueprints.

I reached back out to Audrey Klinkenberg, Saugerties town historian, about whether anyone there have come across any mention of the USS Monitor and Ulster Iron Works since the 2017 news. She said no.

A delicate balancing act during battle

With the Ulster mystery still out there, I asked Hoffman and Hall, who writes the Dead Confederates blog, about the six braces that reinforced the turret. (BTW, it’s possible the forward diagonal supporting brace also had an ULSTER mark and it was eaten by corrosion or is still covered.)

The diagonal braces were installed near the two guns in a claustrophobic space manned by an executive officer and 16 sailors. Like Hall, Hoffman says the 160-ton turret had a revolutionary design for the time.

 Braces highlighted, “U.S.S. Monitor: The Ship that Launched a Modern Navy” by Edward Miller

“The turret is like a suspension bridge,” with the diagonal braces providing balance to “keep it from tipping while firing the gun,” the lead conservator told me. One crew fired a Dahlgren while the other reloaded the second.

Hall says turnbuckles on the braces were a particular benefit at close quarters, as in the Monitor-Virginia battle in Hampton Roads.

“The crew in the turret adopted the practice of firing as the gun muzzles rotated past the target, rather than trying to rotate the turret, lock it in place, and then fire,” he says.

“With both ships maneuvering for advantage, almost at point-blank range, keeping Monitor’s turret moving during the action was essential. The officer commanding in Monitor’s turret, Samuel Dana Greene, described this as the turret’s ‘whirligig motion.’”

In a post on Dead Confederates, Hall describes the turret as “a very crowded and chaotic place.”

Clevis used in aft diagonal support brace (Courtesy The Mariners' Museum and Park)

The “Ulster” brace and its mate have undergone extensive conservation.

Hoffman says in 2016 both got their first round of dry-ice cleaning, followed by another round in 2018, and the aft “Ulster” braces was disassembled. Conservation of its aft clevis (fastener) was completed in 2019. Last year, the forward brace and remaining after-brace components received additional cleaning.

Unroll the turret for cleaning, or leave as is?

The turret currently rests on a lower support pad in a giant Mariners’ Museum and Park tank where it has undergone conservation for two decades.

The guns and braces have been treated in separate areas.

More than 50 maker’s marks associated with Monitor have been noticed over the years, says Hoffman. Roman numerals were spotted on the turret armor plates (the roof is upside down in the tank) and there are Roman numerals on sockets of the canopy stanchion.

The next big thing will be the full cleaning of the turret – but that is still a couple years off. (At right, dry-ice cleaning. Courtesy of Mariners' Museum and Park)

 And there are two considerations:

1. Should the turret be left in its current ring configuration for cleaning? While unrolling the plating might allow conservators to get into its curved layers, replacing rivets afterward may be impossible. Hoffman says the decision was to keep it as is.

2. The team has studied ways to treat wrought iron, which is forged and several inches deep. The turret is too big to clean by hand, so the likely scenario is dry ice, going from solid to gas. The whole idea is to remove ocean salt (chlorides) from the metal, to stem further corrosion.

The lab is working on a plan for the turret treatment, which could take up to eight months.

The turret will be turned right-side up, and the roof taken apart. “There are potentially artifacts still to be found” in the roof because some may be captured in concretion, according to Hoffman. (The remains of two sailors and numerous artifacts were found in the turret.)

Using scaffolding, conservators will clean the ring.

Turret bracing goes down in history, literally

Monitor and Virginia fought to a tactical draw at the 1862 Battle of Hampton Roads.

Hall, author of “Civil War Blockade Running on the Texas Coast,” says Monitor earned the strategic victory because the Confederate ironclad never ventured out again to attack the U.S. fleet.

“The U.S. Navy immediately contracted for new monitors, with several classes of the type entering service before the war ended in 1865. Each new class of monitor was built on the hard-won lessons of those before, with incremental technical improvements in armament, machinery and armor,” he says. (At left, part of the aft diagonal brace assembly. Courtesy of Mariners' Museum and Park)

Monitor sank in the Atlantic storm on Dec. 31, 1862, with the loss of 16 lives.

“The value of Ericsson’s bracing to keep the iron cylinder of the turret rigid proved to be beneficial to history as well, as it ensured that when Monitor capsized and sank in December 1862 after only a few months’ service, the turret fell off the ship but remained intact on the sea floor, from where it would be recovered in one piece in 2002,” says Hall.

An important step in USS Monitor turret conservation reveals an impressive view of the famed Union ironclad's roof

A new view of the ironclad's roof (Mariners' Museum and Park)

Crews using hydraulic lifts have installed new support stands under the massive turret of the USS Monitor so that conservators can have better access to the famed ironclad’s roof.

The work concluded Friday at the USS Monitor laboratory at the Mariners’ Museum and Park in Newport News, Va., museum spokeswoman Crystal Breede said.

The long-anticipated project is a major milestone in the lengthy conservation of the turret, which is upside down, as it was on the sea floor. The turret rests in a 90,000-gallon tank usually filled with a caustic solution that has helped remove tons of marine growth.

Turret rests on temporary lifts (Mariners' Museum and Park)

“The current support structure under the turret will be replaced by eight pedestal support stands to give conservators full access to all sides of the iconic artifact and reveal its roof’s exterior for the first time since the massive ironclad sank in the Atlantic Ocean after the 1862 Civil War battle,” the museum said in a press release before the project began Thursday.

Those new supports were in place by Friday afternoon, Breede told the Picket, and the turret was lowered two inches back into place.

2016 photos of turret interior (NOAA)

The artifact will help further the museum's goal of bringing the human component to a story of the innovative ironclad that tangled with the Confederacy's CSS Virginia in nearby Hampton Roads in March 1862. The USS Monitor, while smaller, was more nimble than the CSS Virginia, and the two vessels fought to what many consider a draw.

The USS Monitor, which had been under tow from Virginia to North Carolina, early on Dec. 31, 1862, slipped beneath the sea, its turret resting upside down on the Atlantic Ocean floor.

The giant artifact was recovered off Cape Hatteras, N.C., in 2002.

Breede said that once the resupport work is done, the tank will be refilled. It may be another three years before the roof is removed. The museum is still years off from turning the turret over, and the goal is having the artifact on public display by 2035.

Crews with old and new supports (Mariners' Museum and Park)